This application claims priority from Japanese Application Serial No. 19009/99, filed Jan. 27, 1999.
The present invention relates to an insertion instrument body used for a medical treatment for distending a narrow portion in a lumen such as a blood vessel of a patient, and to a method for manufacturing the same.
In a conventional treatment for curing a heart disease such as a cardiac angina and a myocardial infarct, a patient is subjected to a series of procedures. The procedures include the steps of inserting a balloon-tip catheter into a narrow portion in a coronary artery in a heart of a patient in vivo, inflating a balloon which is mounted on a distal end of the balloon-tip catheter to distend the narrow portion, and pulling the catheter. A guide-wire is known as an instrument used for introducing the balloon-tip catheter into an inner space of the very thin blood vessel, such as shown in the FIGS. 12 and 13.
FIG. 12 is a general front view showing a distal end of a conventional guide-wire. FIGS. 13(a) and 13(b) are general front views showing a state that a balloon-tip catheter is introduced into a blood vessel by using the conventional guide-wire shown in the FIG. 12, and are partially cross sectional views. A reference numeral 1 in the FIG. 12 denotes a distal end of the guide-wire, and a reference numeral 2 denotes a flexible metallic core portion. An outer face of the metallic core portion 2 is covered with a not-shown sleeve as a coating formed by spraying a high molecular resin such a polytetrafluoroethylene, namely PTFE and so on. A coil is formed to surround the distal end of the metallic core portion 2 to form a coil spring portion 3. Since X-rays are not able to pass through the coil spring portion 3, the distal end of the guide-wire 1 is clearly observed by the X-ray images. Therefore, a position of the distal end of the guide-wire 1 can be exactly controlled within the patient body by X-ray images.
As illustrated in the FIG. 13(a), since the guide-wire 1 can proceed deeply in a blood vessel 4 such as the coronary artery of the heart in vivo, a balloon-tip catheter 5 can be easily introduced into a narrow portion 6 of the blood vessel 4 by using the metallic core portion 2 as a guide instrument. In the narrow portion 6 of the blood vessel 4, an inner space can be produced by increasing a balloon 7 of the balloon-tip catheter 5 as illustrated in the FIG. 13(b).
Sometimes, the narrow portion 6 in the blood vessel 4 is almost blocked up so that the inner diameter becomes so small that the distal end of the guide-wire 1 can narrowly be inserted into the narrow portion 6. In this case, emergency procedures are taken so that the inner diameter of the narrow portion 6 in the blood vessel 4 is gradually distended. The procedures include the steps of preparing a plurality of catheters having different outer diameters; and inserting catheters one by one in ascending order of outer diameter into the narrow portion 6 along the guide-wire 1 which has already been inserted thereinto. By using a plurality of catheters, time required for such an operation program is prolonged and the expense is increased. In case that the catheters cannot be introduced into the blood vessel, open-heart surgery must be performed, increasing trauma to the patient.
In the narrow portion 6 of the above blood vessel 4, an inner space is obtained by means of the metallic core portion 2 of the guide-wire 1. It is therefore required an insertion instrument body which can promptly perform the distention of the narrow portion 6 in order to maintain the inner space above be developed.
An object of the present invention is to provide an insertion instrument body and a method for manufacturing the same, the insertion instrument body able to securely distend a narrow portion of the blood vessel being almost blocked up.
According to one aspect of the present invention, there is provided an insertion instrument body to be inserted into a lumen in vivo, including: a longitudinal base portion insertable into the lumen in vivo; a distending portion distending the lumen in vivo and arranged on an outer face of the distal end of the base portion, wherein the distending portion extends in a longitudinal direction of the base portion and is at least partially formed of a shape-memory material which displaces in an intersecting direction with respect to the longitudinal direction of the base portion at a temperature above a transforming temperature of the shape-memory material and returns to an original shape; and a power supply means for heating the distending portion to a temperature above the transforming temperature.
Here, xe2x80x9cinsertion instrument bodyxe2x80x9d means an instrument for distending an inner space of lumen, tubes and blood vessels, and more concretely includes a surgery instrument such as a guide-wire, a catheter and so on with a distending portion made of a shape-memory material. In this specification, xe2x80x9cguide-wirexe2x80x9d means a thin guide member to be inserted in the lumen prior to the catheter. xe2x80x9cCatheterxe2x80x9d means a cylindrical, hollow member having a radius slightly greater than that of the guide-wire, and being able to inject or suck liquid. Moreover, the catheter can be used to secure an inner space within a route such as a blood vessel. xe2x80x9cShape-memory materialxe2x80x9d means a high molecular weight material such as a metal, resin or the like which has a shape-memory effect (SME) and a superelastic effect (SE). Although SE is taken at the room temperature lower than a transforming temperature, SME is taken at a temperature higher than the transforming temperature. xe2x80x9cSMExe2x80x9d means a property that causes the rigidity of the shape-memory material to be increased so that the material returns to a memorized original shape. Further, the arrangement of the distending portion on the outer face of the distal end of the longitudinal base portion described above includes two embodiments. In the first embodiment, the distending portion includes a cylindrical body having an inner space to which the base portion is insertable, and a rod-shaped portion formed to be integrally with the cylindrical body. Moreover, the cylindrical body is mounted on the distal end of the longitudinal base portion so as to cause an inner wall of the cylindrical body to come into contact with the outer face of the base portion. In the second embodiment, the distending portion does not include the cylindrical body as described above, and includes only the rod-shaped portion displaceable as a result of the shape-memory effect. The distal end of the base portion consists of some continuous parts having different outer sizes such as different outer radii and so on. Therefore, the outer face of the base portion at an optionally selective position is defined by the outer size such as an outer radius at the optionally selective position in the distal end thereof.
According to another aspect of the present invention, there is provided a method for manufacturing an insertion instrument body to be inserted into a lumen in vivo, comprising the steps of: preparing a longitudinal base portion insertable into the lumen in vivo; forming a groove extending approximately in an axial direction of a cylindrical body on a part of an outer surface of said cylindrical body to produce at least one rod-shaped portion on the outer surface of said cylindrical body, wherein said cylindrical body is formed of a shape-memory material and is mountable on said base portion; providing a shape-memory to said rod-shaped portion to define the total of said cylindrical body as an distending portion for distending the lumen in vivo, wherein the shape-memory is defined by displacing said rod-shaped portion in an intersecting direction with respect to the longitudinal direction of said base portion at a temperature above a transforming temperature of the shape-memory material when said rod-shaped portion is fixed to an outer face of the distal end of said base portion so that said rod-shaped portion approximately extends along a longitudinal direction of said base portion and returns to an original shape; fixing said cylindrical body to the outer face of the distal end of said base portion; and connecting a power supply means to at least said distending portion, said power supply means heating said distending portion to a temperature above the transforming temperature. This manufacturing method relates to an insertion instrument body regarding the embodiment described above. Here, the groove to be formed on the cylindrical body may be limited to only one such groove. In this case, it is possible to form one rod-shaped portion by forming one groove having a large width.
An insertion instrument body 8 includes a longitudinal metallic core portion 2, a distending portion 9 and a power supply means 10. The metallic core portion is inserted into a lumen such as a blood vessel. The distending portion 9 is fixed to an outer face of the metallic core portion 2. The power supply means 10 heats the distending portion 9 above a transforming temperature. The distending portion 9 includes a cylindrical portion 11 which is mountable on the metallic core portion 2; and a plurality of rod-shaped portions 12 which are integrally formed in the cylindrical portion 11 and which are made of a shape-memory material. The rod-shaped portion 12 returns to an original shape by displacing in an intersecting direction with respect to a longitudinal direction of the metallic core portion 2. An electrical insulating layer 21 is formed on an outer surface of the metallic core portion 2, and the electrical insulating layer 21 is covered with a flexible sleeve 22. A power supply means 10 is constituted of the metallic core portion 2, the flexible sleeve 22, a power source 24 and a switch 25.
According to further another aspect of the present invention, there is provided a method for manufacturing an insertion instrument body to be inserted a lumen in vivo, comprising the steps of: preparing a longitudinal base portion insertable into a lumen in vivo; preparing at least one rodshaped body which consists of a shape-memory material; providing a shape-memory to said rod-shaped body to define the total of said cylindrical body as a distending portion for distending the lumen in vivo, wherein the shape-memory is defined by displacing said rod-shaped portion in an intersecting direction with respect to the longitudinal direction of said base portion at a temperature above a transforming temperature of the shape-memory material when said rod-shaped body is fixed to an outer face of the distal end of said base portion so that said rod-shaped portion approximately extends along a longitudinal direction of said base portion and returns to an original shape; fixing said distending portion to the outer face of the distal end of said base portion so said distending portion approximately extends in the longitudinal direction of said base portion; and connecting a power supply means to at least said distending portion, said power supply means heating said distending portion to a temperature above the transforming temperature.
This manufacturing method relates to an insertion instrument body regarding the second embodiment as described above. Here, the power supply means constitutes an electric circuit including the distending portion. The electric circuit can optionally include the longitudinal base portion. When the electric circuit includes both the distending portion and the base portion, the distending portion must be electrically insulated from the base portion. The rod-shaped portion or member means a thin, longitudinal portion or member such as thin plate, wire and so on. The thickness of the rod-shaped portion or member is suitably determined in view of the outer size of the base portion.